This past weekend saw a surge in demonstrations demanding justice in the case of the Ayotzinapa students, with protests targeting retail stores promoting their Buen Fin discounts, Mexico's equivalent to the US Black Friday sales. The tension in Mexico City worsened on Saturday, when a local police officer had an altercation with students holding an assembly at the National Autonomous University of Mexico (UNAM), shooting and injuring two participants. Given that the UNAM has autonomy, the question has been raised of why officer was even there in the first place. Clayton Conn reports from Mexico City. teleSUR